<?php
	session_start();
/**
 * vCode(m,n,x,y) m个数字  显示大小为n   边宽x   边高y
 * 自己改写记录session $code
 */
 
vCode(4, 20); //4个数字，显示大小为15
function vCode($num = 4, $size = 20, $width = 0, $height = 0) {
 !$width && $width = $num * $size * 4 / 5 + 5;
 !$height && $height = $size + 10; 
 
 // 去掉了 0 1 O l 等
 $str = "23456789abcdefghijkmnpqrstuvwxyzABCDEFGHIJKLMNPQRSTUVW";
 $code = '';
 for ($i = 0; $i < $num; $i++) {
  $code .= $str[mt_rand(0, strlen($str)-1)];
 } 
 // 画图像
 $im = imagecreatetruecolor($width, $height); 
 // 定义要用到的颜色
 $back_color = imagecolorallocate($im, 235,236,237);
 $boer_color = imagecolorallocate($im, 118, 151, 199);
 $text_color = imagecolorallocate($im, mt_rand(0, 200), 
				mt_rand(0, 120), mt_rand(0, 120)); 
 // 画背景
 imagefilledrectangle($im, 0, 0, $width, $height, $back_color); 
 // 画边框
 imagerectangle($im, 0, 0, $width-1, $height-1, $boer_color); 
 // 画干扰线
 for($i = 0;$i < 5;$i++) {
  $font_color = imagecolorallocate($im, mt_rand(0, 255), 
				mt_rand(0, 255), mt_rand(0, 255));
  imagearc($im, mt_rand(- $width, $width), 
		  mt_rand(- $height, $height), mt_rand(30, $width * 2), 
		  mt_rand(20, $height * 2), mt_rand(0, 360), mt_rand(0, 360), $font_color);
 } 
 // 画干扰点
 for($i = 0;$i < 50;$i++) {
  $font_color = imagecolorallocate($im, mt_rand(0, 255),
  mt_rand(0, 255), mt_rand(0, 255));
  imagesetpixel($im, mt_rand(0, $width), mt_rand(0, $height), $font_color);
 } 
 // 画验证码
 @imagefttext($im, $size , 0, 5, $size + 3, $text_color, 'SIMSUNB.TTF', $code);
 $_SESSION["code"]=$code; 
 header("Cache-Control: max-age=1, s-maxage=1, no-cache, must-revalidate");
 header("Content-type: image/png;charset=gb2312");
 imagepng($im);
 imagedestroy($im);
}
?>